I have a 98 F-150 4x4 with the 5.4L engine with 120K miles. For a while, I've noticed that my truck would use/lose about a quart of oil between oil changes (3000 miles). However, over the past few oil changes I've noticed an increase in oil loss in less mileage. It's been only 2K miles since the last oil change, and now there is barely any oil registering on the dipstick!

Have any of you had this problem before? There is never any black smoke coming from the exhaust, and there are no leaks to be seen. Where can the oil be going? I bought the truck used in 2001 with 60K miles on it. Maybe the guy who had it before me never changed the oil? I'm at a loss, and if there's not an easy explanation/solution to this problem I'm going to unload this thing ASAP.

Thanks,

Bigblack

 

What oil are you running?

 

I run Motorcraft 10w30 when Wally World has it. When they're out of the Motorcraft, I use Castrol in the same weight.

 

My father said that he would never run castrol. He said it sludges up too bad. But I don't know that from personal experience. Why don't you switch brands. I like JD oil, but most folks don't want to pay $2.00 a quart for straight dino oil. But my truck doesn't burn it. Just try another brand, and see what happens. It can't hurt. Oh, and replace the pcv valve. The dealer will GIVE you a new one.

 

That's the third time I've heard "replace the PCV valve". How could that little valve be responsible for 3-4 QUARTS of oil loss between changes?

I guess I just don't understand what the PCV valve does.

 

I have been using Caster oil for more than 20 years with no sludge. I had 80 thousand on my camero when I rebuit the engine (My Fault). Not a drop of sludge. Oil was changed every 3000. Most oils are good. Just do not mix them and change with regular schedule. The big problem is using different oil at each oil change.

 

The PCV valve evacuate all the vapors from the crankcase. therefore reducing pressure, reducing oil leakage from seals. In your case you are most likely losing oil from the oil lines, possibly head gaskets. My 98 4six loses quite a bit of oil between changes. I have leaky head gaskets, and leaky oil lines. Check the lines, check the gaskets, check around the oil pan. If you find a heavy build up of gunk around any of these, clean the area with brake cleaner than recheck that area after a couple hundred miles of driving.

Also, Castrol oil is horrible chit. I used it in my camaro and it was thick and blackened after a couple thousand miles. DONT USE IT. Now I strickly use Motorcraft oil & filter

 

If it's leaking, fix the leaks. If it's consuming the oil, it can come from a number of places, but the most direct route to the combustion chamber is via the intake, through the PCV valve and hoses. It can be caused by excessive blow-by from a well-used engine, or by a stuck PCV valve.

Another function of the PCV is to prevent a back-fire from blowing out your oil pan:

For the record, on a 98, anything less than one quart consumed per 900 miles traveled is not considered excessive. Yes, that means that with the recommended 5000 mile oil change interval, it's possible to go through more than 5 quarts without being considered 'excessive'. (although many would beg to differ, that's Ford's official spec)

 

I would start simple and cheap, and being that it looks like yours was never changed. I would change the PCV valve first. They can be had at any auto parts store for less than $5.00.

 

AS I STATED EARLIER, they are FREE at your dealership. There's no reason not to change it. All engines burn oil though. Change brands, and if that doesn't help, don't worry. Just keep the oil topped off and you will get 200,000 more miles out of it.

 

Fords standards are now 3,000 miles. Even though it is probably just for profit reason, you should still change it every 3K. I change mine at 2,500 and the oil is still blackened, I wouldnt dare go to 5k.

 

Nay... Ford standards are now 5000 miles, except for heavy duty use. Used oil analysis shows conclusively that, in all but the most extreme conditions, 5000 mile intervals are more than sufficient.

Changing it every 3000 miles isn't going to hurt a thing, but it's not 'Ford's policy'.

 

Well from what I'm told, which is probably just a bit to make money, I have to label the oil sticker for 3,000 miles/ 3 months.

 

That's rediculous. You're wasting your money. Ford standards are 5,000 for trucks and MORE for cars! If yours is leaking as much as you say, you shouldn't ever have to change it anyway.

 

How did you find out that PCV valves are free at dealerships? So I could just walst into the parts department and ask for a PCV valve and they will give me one? What I am trying to ask is, why are they free at the dealership?